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Oct. 15, 1929. M. MOELLER ETAL, 1,732,060

ARRANGEMENT FOR REGULATION OF STEAM BOILERS Filed March 4, 1927VVEA/TURj MAX Tran-1.1. e-

TTANFRED .imaemlm KARL 16.1155- '35 is about 5.10"? watt.

Patented Oct. 15, 1929 UNITED STATES PATENT OFFIE MAX IIIOELLER AND MANFRED SCHLEICHER, F BEBLIN-CHARLOTTENBUEG, ANT KARL KLUGE, OF BERLINJVILMERSDORF, GERMANY, ASSIGNORS TO SIEIMENS & HALSKE,AKTIENGESELLSCHAFT, OF SIEMENSSTADT, NEAR BERLIN, GERMANY, A CORPORA-TION 0F GERMANY ARRANGEMENT FOR REGULATION OF STEAM BOILERS Applicationfiled March 4, 1927, Serial No. 172,913, and in Germany March 9, 1926.

The present invention relates to a new and useful arrangement forautomatically setting the regulating organs of steam boilers.

In such arrangements difliculties arise from the circumstance that themembers for regulating the steam boiler as for instance the conveyorgrate, the organs for regulating the air supply and the flue gas escape'etc.,"require very large s'etting forces, while the measuringinstruments for controlling the adjustment of these members have onlyvery small turning moments. Such instruments are necessary for measuringthe draught of air, the temperature, the carbonic acid'contents of theflue gas etc.

In 'order to overcome these difficulties a bridge connection is usedaccording to the invention as an arrangement for the automaticregulation of steam boilers.- The resistance in one'branch of the bridgeis regulated by means-of a measuring'device which may indicate forinstance the steam quantity or another factor. The current in thediagonal branclrof the bridge controls a motor which moves the boilermember to be regulated. In dependence of the adjustment transmitted tothe member another branch tance of the bridge is regulated as long asthe bridge equilibrium is re-established.

In this manner an extraordinary increase of power is produced when usingsuitable constructional elements. The energy necessary to deflect thepointer of a sensitive measuring instrument in the 50th part of itsrange Such a deflection is sufiicient for starting an eler-tromotor of500 watts with the aid of a bridge connection. Therefore the use of abridge connection for the regulation of the boilers provides thepossibility of increasing the effect of a small controlling force withrespect to the regulation. Moreov r, the elements of the newerrangementhave not only a high sensitiveness but also such a strength as to affordcfficiency in service.

Another feature of the invention consists in providing an auxiliaryforce produced by means of an auxiliary device for controlling theregulation movements. said auxiliary device being operative only duringperiodical intervals which can be set at will. This auxiliary devicewhereby the auxiliary force is produced coacts with a measuringinstrument in such amanner that a determined amount of the regulatingmovement will result from the operation of the auxiliary device whichmay be for instance a depression bar. The depression bar may close acontact either prepared by the measuring device for regulating a branchresistance of the bridge or by the relay lying in the diagonal branch.In both cases, it is possible to produce a regulation of the boilermember to be regulated, only when the controlling instrument indicates apredetermined deflection from its normal position. Thereby the drawbackof a too lar e amount of regulation is avoided in a simp e manner. 7

In the drawing several embodiments of the invention are represented byway of example. Fig. 1 illustrates a first example of execution. t Fig.2 is a second embodiment of the invenion.

Fig. Sshows a side elevation, and Fig. a front view of the controllingrelay of Fig. 2.

' Referring to Fig. 1 the steam boiler 1 is provided with a superheater.The superheated steam flows through the conduit 2. A thermo couple 3 anda galvanometer 4 are adapted to measure the temperature of the steam. Bymeans of a lever 19 a membernot shown-for regulating the entrance of thehot flue gases to the superheater can be adjusted. The lever 19 isconnected by a rod 5 to a screw-nut 6 which moves along a spindle 7driven by a motor 8. The screw-nut 6 carries a contact 9 which slides onthe resistance 10. A second resistance 11 extends below the pointer 12of the galvanometer 4, while a depression bar or depressor 13 isarranged above. The depressor causes the pointer 12 to make contact onthe resistance 11 at periodical intervals. The means for operating thedepressor 13 are not represented in Fig. 1. The resistances 10 and 11are connected together to form a Wheatstone bridge, which is fed fromthe direct current lines 20. In the diagonal branch, leading from theaxis of the pointer 12 to the sliding contact 9, is inserted a. relay 16which controls the circuit of the motor 8. lVhen the upper relaycontacts are closed the motor is connected to a battery 17 and attheclosing of thelower contacts to a battery 18, the current in themotor circuit flowing then in opposite'direction.- 'Therefo're the motorwill start for rotatiofi either to the right or to the left.

- The pointer 12 is pressed down on the resistance 11 at periodicalintervals. If the superheated steam has reached the deslred temperature,the relay 16- is 'not excited.- If the pointer 12 however makes adeflection the equilibrium of the bridge is disturbed. Then at theclosing. of the .c-ontacts ll, 12 the relay 16 is excited and themotori8 moves theleiver 19by meansio fthe elements 7. f3, 5. The motoronly turnsthe spin dle 7 as longas the contaet ll, 12 remains closed.When the. de-. presso r.13.n1ovesiipwards. and breaks the contact 1 1,12 ,theinotor 8 stops. The time in? tervalsbetweenthe successivecontacts and the duration ofeach cont-act may. be set inaccordancewiththe special conditions of working. 7

2 represents another. embodiment of the invention in.whi'ch theperiodically aeting auxiliary force is etfective at the relay in thediagonaLbranclr of the bridge. 22 1s a steam ,boiler 1w-ith".a steampiping to wh ch a pressure measuring device 3 24 i connected. The piston25 of this device turns a shaft 27 by means of a-suitablegearing 26.Preferably thepiston 25 isco ntinuously rotatedm order to compensate forlosses due .to friction. On the shaft 27 there is arranged a regulatingresistance. 28. This resistance is constituted by a hollow ring ofinsulating material n hich isplaced a re-sistancewire and a suitable.quantity. of. mercury completely or part- ].v short circuiting thisresistance according to the positionofthe hollow ring. The resistance28,belongs to a lVheatstone bridge 29 which besides comprises constantresistances 30.31.32 and a second regulating resistance 33 ofthe, sameconstruction as the first regulating resistance 28. In the diagonalbranch of thebridge a relay .35 is arranged which controls amotor 34.The construction of this relav. will be described with reference toFigs. 3.arid 4. The motor 34 moves the regulating member 36 for the airsupply of the steam boiler 22. The air enters into the boiler through atube37 to which a device-38 for measuring the draught is connected. Theessentiaipart of thisdevice is a bell 39 which inovesnp and down andturns a shaft 42 by means of a toothed rod .40 and a spur Wheel 41. Theshaft 42 carriesthe-regulating resistance 33.

Referring to Figs. 3 and 4 the relay com.- prises a pointer 48 with alittle plate 49 at its free end. The plate 49 plays above twosuppartsfiq gd. S neca? ed from each other y a gap. Under thi gap fourplate springs 5252 are horizontally fixed. These springs are adapted tocoact with four counter cont2 1ct s 53?53 for controlling thecircuit ofthe motor 43 for clockwise and counterclockwise rotation. Over thepointer 48 two depression bars or depressors 54 and 54" are arrangedside by side movably about the aiiis 55. Each of the dcpressors .54 and54 is coupled by means of-the elements 56,57 to an angle lever 58 whichnormally is only influenced by a spring 59. The free end 60 of the lever58 serves as the armature of an electromagnet (32 which is excited by acoil 61. The circuit of the coil 61 is closed and interrupted inperiodical intervals. For. this purpose (see Fig. 2) one end of the coil61 is connected over a wire 63 to the positive pole 64 of a source ofdirect current and the other end over the wire 65 to a contactpiece 66.The contact piece 66 is fixed upon, a drum 67 which is rotated with constantspeedby a motor 68. I

The cont-act piece 66 touches at each rotation of the drum a stationarybrush-69 which is connected over the wire 70 to the negative pole 71 ofthe source of current. Each time the magnet- 62 is electrically excitedthe end 60 of the lever 58 attracted in opposition to the forceof thespring and, by the coupling 56, 57, the depressor 54 is ,moveddownwards. If the pointer 48 just. in this moment stands below thedepressor no contact is closed at 52*; 53 and 52*, 53", because theplate 49 prevents the depressor from entering the gap between theelements 50, 51. If the pointer however has a position 'outof the rangeof the depress sor the depressor reaches the position 54, Fig. 3)represented in dotted lines, whereby the plate springs 52 and 52 in theposition 52 shown in dotted lines touch the countercontacts 53 and 53"and therefore close the motor circuit. The manner of operation of thedepressor 54" which actuates the contact springs 52 and 52 is quite thesame as that described with respect to the depressor 54*.

It would be possible to mount the contacts 5252 on the front sides ofthe depressor without changing the manner of operationv above described.The contacts control the circuit of the motor 34 for turning to theright or to the left, the motor being connect-ed to the contacts bymeans of the lines 72 and 73. A suitable sourceof current is connectedat 74, Fig. 4.

The workingof the arrangement shown in Fig. 24 is as follows: If theaxis of rotation of the resistance 28 is driven by the steam.

measuring device 24. the equilibrium in the bridge 29 will be disturbed.In the diagonal branch will then flow a current which will produce adeflection of the pointer 48 of the measuring instrument 35. Thedepressors 54, 54 are attracted and released at regular time intervals,which can be set at will, byits electromagnet 62 which is energized anddeenergized by means of the time switch gear 66, 69. Accordingly in themanner above described the contacts 52, 53* and 52, 53 or the contacts52, 53 and 52, 52 are closed and opened owing to which the motor 34 willbe switched on. As long as the contact is maintained, the motor 34 willrotate and regulate the damper 36. Thereby the air supply will change,until the resistance 33 will be regulated by the device 38 in such amanner that the equilibrium in the bridge 29 will be re-established.

An essential advantage of this embodiment of the invention is that by asuitable choice of the time intervals for the working of the auxiliaryforce in the diagonal conductor there can be set at any time that timedependence of the sequences of working of the single switch members,which corresponds to the working conditions. In this way it is possibleto avoid entirely or at least practically, any swinging of the motor 34about the desired setting position.

By the term operating characteristic as employed in the claims is to beunderstood a factor or condition connected with the operation of a steamboiler and usually measured so as to be kept within certain limits toobtain optimum or predetermined results; such operating characteristicincludes the pressure or quantity of the steam produced, the temperatureof the steam, the composition of the flue gases, etc.

Whatwe claim as our invention and desire to be secured by Letters Patentis:

1. In an arrangement for the regulation of steam boilers including aregulating member, the combination of a first resistance, an instrumentadapted to be adjusted automaticaL ly in response to changes in anoperating characteristic of the steam boiler and adapted to regulatesaid first resistance, a motor for moving said regulating member of thesteam boiler, a relay for controlling the circuit of said motor. asecond resistance, means for regulating said second rcsistanceinaccordance with the actuation of said regulating member by said motor,electrical connec tions between said first resistance, said secondresistance and said relay respectively arranged in such a manner as toform an automatically actuating bridge with said relay in its diagonalbranch, and auxiliary means coordinated to one element of said bridgeand adapted to make the bridge operative only during periodicalintervals.

2. In an arrangement for the regulation of steam boilers including aregulating member, the combination of a first resistance, an instrumentadapted to be adjusted automatically in response to changes in anoperating characteristic of the steam boiler and adapted to regulatesaid first resistance, a motor for moving said regulating member of thesteam boiler, a relay for controlling the circuit of said motor, asecond resistance, means for regulating said second resistance inaccordance with the actuation of said regulating member by said motor,electrical c0nnections between said first resistance, said secondresistance and said relay respectively arranged in such a manner as toform an automatically actuating bridge with said relay in its diagonalbranch, and a depression bar acting upon one of the elements of thebridge for making the bridge operative only during predeterminedintervals.

3. In an arrangement for the regulation of steam boilers including aregulating member, the combination of a first resistance, an instrumentadapted to be adjusted automatically in response to changes in anoperating characteristic of the steam boiler and adapted to regulatesaid first resistance, a motor for moving said regulating member of thesteam boiler, a relay adapted to prepare a controlling contact for saidmotor, a depression bar for closing the contact of said relay onlyduring predetermined intervals, a second resistance, means forregulating said second resistance in accordance with the actuation ofsaid regulating member by said m0- tor, and electrical connectionsbetween said first resistance, said second resistance and said relayrespectively arranged in such a manner as to form an automaticallyactuating bridge with said relay in its diagonal branch.

4. In an arrangement for the regulation of steam boilers including aregulating member, the combination of a first resistance, an instrumentadapted to be adjusted automatically in response to changes in anoperating characteristic of the steam boiler and adapted to regulatesaid first resistance, a motor for moving said regulating member of thesteam boiler, a depression bar for closing the contact of said relay, anelectromagnet for moving said depression bar, a time switch forenergizing said electromagnet only during predetermined intervals, asecond resistance, means for regulating said second resistance inaccordance with the actuation of said regulating member by said motor,and electrical connections between said first resistance, said secondresistance and said relay respectively in such a manner as to form anautomatically actuating bridge with said relay in its diagonal branch.

5. As an arrangement for the regulation of steam boilers including aregulating memher, an automatically acting bridge connection including afirst resistance wire arranged together with a quantity of mercury in ahollow ring of insulating material, said ring being mounted on a shaft,a second resistance, and a relay in the diagonal branch, in combinationwith an instrument adapted to be adjusted automatically in response tochanges in an operating characteristic of the steam boiler, andadaptedtoturn the shaft of said first resistance, a motor-for adjusting saidregulating member of the steam boiler, said motor being-controlledbysaid relay and means for regulating said second resistance inaccordance with the actuation of said regulating member by said motor.

6. As an arrangement for the regulation of steam boilers including aregulating m'ember, an automatically acting bridge-connection includinga first and a second resistance and a relay in the diagonal branch, bothresistances comprising a resistance wire and a quantity of mercuryarranged within a hollow ring, in combination with an instrument adaptedto be adjusted automatically in response tochanges' in anoperatingcharacteristic of the steam boiler, said instrument beingadapted to move the shaft of said first resistance, a depressor forclosing'th'e contact of said bridge relay only during predeterminedintervals, a motor for adjusting said regulating member of thesteam-boiler, said motor being controlled-by said bridge iclay, contact,and means-for automatically moving the shaft of's'aid second resistancein accordance Withthe actuation'of said regulating member bysaid motor.

7; In aregulatingsystem for steam boilers, including aiWV'heatstonebridge, the combination of apointer: instrument 1 in thediagonal branch-.of saidbridge, an electric circuit, a group of movablecontacts controlling said circuit, and-anauxiliaryedevieerfor actuatingsaid contacts-to close'said circuit, the pointer of .saidinstrument,-when the bridge is in equilibrium,-preventing said auxiliary devicefrom, actuating said contacts, and

when said equilibrium is disturbedpermitting actuation of said contactsby said device.

8. In a regulating system for steam boilers, including a \N'heatstonebridge,-the combination of a motor circuit, a group of-movable contactscontrolling said circuit, adepression bar spaced from said group ofcontacts for depressing the latter to close-said motor circuit, and apointer instrument-inthe diagonal branch of said bridgehavingEits'pointermov able in the space between said depression bar andgroup of contacts, said pointer, when the bridge is in equilibrium,preventing saidde pression bar from depressing said contacts, and whensaid equilibrium is disturbed permitting depression of said contacts bysaid bar.

9. In a regulating system for steam boilers, including a \Vheatstoncbridge, the-combination of a motor circuit, a group of stationarycontacts in said motor circuit, a group of movable contacts co-operatingwith said stationary contacts to control said motor circuit,

two depression bars lying side by side and spaced above said movablecontacts,,for depressing the latter into contact with said stationarycontacts, and-a pointer instrument in the diagonal branch of said bridgehaw ing its pointer movable inthe space between said depression bars andsaid group of: movable contacts, said pointer, when the bridge is inequilibrium, preventing said depression bars from depressing saidmovable contacts, and when said equilibrium isdisturbed permittingdepression of certain of said'con tacts by one of said depression barsand preventing the other bar from functioning.

10. In an arrangement for the automatic regulation of steam boilersincluding a regulating member, the combination of a-first resistance, aninstrument adapted to be adjusted automatically in response to changesin an operating characteristic of assteam boiler and operativelyassociated withsaid resistance to varythe same upon deflection from anormal position, a regulating member, a motor connected to said memberto adjust the same, an electrically responsive device for controllingsaid motor, a second re-' sistance, means for regulating said secondresistance in response to the actuation of said regulating member, andelectrical connections between said first resistance, said secondresistance and said device so arranged as to form a bridge withsaid-device'in the'diagonal branch.

In testimony whereof we afiix-our signatures. I MAX MOELLER. MANFREDSCHLEIC'H'ER. KARL KLUGE.

